Aging, ill, disabled or indoor cats may have a difficult time losing weight because they often don't get much exercise.
Special-needs cats need to move more slowly, says Jim Boelke, president of Cat Dancer Products Inc. in Neenah, Wis.
"You won't get a backflip out of a 15-year-old cat," he says.
Dietary needs may be limited as well.
"Senior cats and indoor-only cats tend to need fewer calories," says Kurt Iverson, external relations manager for The Iams Co. in Dayton, Ohio.
Many manufacturers make specially formulated diets for indoor and senior cats. These diets may have added vitamins and ingredients to help boost their immune system and improve joint health.
Certain types of toys may be a good method to lure older or disabled cats into exercise.
"Catnip toys that are use-at-your-own-level-type toys are more appropriate for a cat that may not be physically able to move around like a kitten does," says Amy Brickle, product manager at the Golden, Colo.-based Kong Co.
If you see a sudden change in weight, or if your cat is morbidly obese, always see a veterinarian before making any dietary changes.
"Obesity can also be an indicator of underlying conditions, such as diabetes, which can best be treated by a health professional," Iverson says.